Aerial navigation



CROSS REFERENCE S. l... EGENAS AERIAL NAVIGATION l June; 4, 1940.

Filed Dec. 9, 1937 Patented June Il, 19dnarran stares I, Laatst ancrer. Nay/resarcir Severin L. Egenas, Ghisa-go, lil., assigner toA Hermann Hille, Chicago, Kil.

Application December 9, 1937, Serial No.; Wil-,9&9

1 Claim.

This invention relates to improvements in method and apparatus for the navigation of aircraft, and particularly to a method and apparatus for the determination of wind direction and velocity from aircraft While in flight.

The main objects of this invention are to -provide an improved method for determining absolute wind direction and velocity from aircraft in night; to provide an improved method for determining the necessary compensation for lateral drift of aircraft while navigating a predeterminedcourse; to provide an improved method of navigating aircraft; to provide an improved apf paratus for determining wind direction and velocity from aircraft while in iglit; to provide such apparatus to enable the maintenance of a ,substantially constant ground speed While detverrnining Wind direction and velocity; to provide such apparatus arranged to indicate varia tions in ground speed or momentum; and to provide such apparatus arranged to indicate changes in momentum or ground speed While variations in air Aspeed are being observed.

A specific embodiment of this invention is showrrn the accompanying drawing, in which:

Fig. l is aview of an aircraft illustrating diagrammatically the manner in which the improved apparatus may be positioned within the aircraft.

Fig. 2 is a view in vertical elevation showing apparatus for indicating a change in momentum or ground speed.

Fig. 3 is a face View of a control panel embody ing the instruments for carrying out the improved method of navigation, and,

Fig. 4 is a course diagram illustrating the manner in which the improved method of navigation is accomplished.

Knowledge of the absolute wind direction and velocity is of great importance from the standpoint of safety, particularly in blind flying, since it enables a pilot to determine his drift and to thereby stay in his predetermined course. Heretofore in the navigation oi aircraft, it has been impossible for the pilot or navigator to Adetermine wind direction and velocity, over the course that it is desired to follow, from the aircraft while it is in blind flight; and it has been estimated that approximately half the transport accidents could have been obviated were these factors known.

My improved method of aircraft navigation is intended to overcome this diiculty and involves a series of relatively simple procedural steps whereby w nd direction and velocity can be quickly and substantially accurately determined from an aircraft while it is flight Without taking the ship far from its predetermined course and whereby the ship will be substantially on its predetermined course at the termination of the necessary observations. 5

In the practice owmy improved method of navigation, and while in full fright, the aircraft is navigated through a 360 horizontal turn, or such turn as may be necessary, while it is :naintained at a substantially constant speed relative to the ground and during such turn observations are made of the air speed as indicated by suitable apparatus for that purpose, the rnammum and minimum air speed attained being noted, together with the direction in which the aircraft 1 is dying at the time of each such maximum and minimum air speed indications.

Thus, after the maximum and minimum air speeds are determined and the direction of flight atthe maximum and minimum points is had, the wind direction and velocity may be determined by nnding half the difference between the maximum and minimum air speeds, which is Isubstantially the actual or absolute wind velocity' and by noting the direction in which the aircraft is iying at the point of minimum speed, which is the actual or absolute wind direction.

An essential factor in the practice of my irlvention is the maintenance of a substantially constant ground speed during the time that the maximum and minimum ein-speed observations are being made and for this purpose means are provided to automatically indicate any change in momentum, or inertie, of the aircraft, thus 'iicating to the pilot whether he is gaining or 35 losing speed relative to the established speed at which the aircraft is desired to be kept moving during the period of observation, so that proper compensation can be made to negative or overcome any observed speed change. Such compensation may be accomplished by increasing or decreasing the speed of ille motor or motors driving the aircraft, or ry divina or climbing to .increase or decrease 'the Speed of the aircraft respectively, so that the desired ground speed will be maintained A Change 0'. momentum indicating device suitam@ for this purpose is illustrated in 2 of the drawing, ind as shown comprises indicating means Sensitive to changes or variations in momentuin or inertia combined with a constant level de vice arranged to keep the inertia change indicator level with respect to the earth irrespecti1 e of changes in the flight attitude of the aircrf it in which the device is mounted.

As shown, the inertia change indicator comprises an elongated tube i curved upwardly from its middle toward its ends, and supported at its ends in a U-shaped bracket 2. A ball of mercury 3 is contained in the tube l and the tube is disposed so that its central portion will be lowermost with the mercury normally lying therein. Also a plurality of contacts arc disposed in the upwardly curved portions of the tube i on each side of the tube center, which contacts are provided with suitable electrical connections and arranged to complete respective electrical circuits when engaged by the mercury 3.

In the form shown there are three longitudinally-spaced contacts provided on each side of the tube center, the central contacts fi and im of each group respectively, being connected to a common source of electromotive force, such as a battery I5 and the outside contacts, 5, 5J, 1 and 'Li being each connected to one side of a respective light source or other indicating means 8, ttl, 9 and QJ, from which suitable connec# tions are made to the opposite side of the battery 5. In the arrangement shown, the indieating means 3 and show acceleration and l and 9.2 show deceleration.

Thus, when the tube i is maintained in a constantly level position with respect to the earth, any change in momentum or inertia'oi the device will cause the ball of mercury 3 to shift backward or forward according to the direction in which the change is taking place. Such shifting of the ball of mercury 3 will cause it to engage either the contacts fi, Ei, and or the contacts M, El, and (J, so as to complete a circuit between the central contact and either one or both the outside contacts, thereby energizing the respective light sources or other indicating means to produce a visual indication of the momentum or inertia` energizing the light source 8 only. A greater amount of inertia o1' momentum change in the same direction will cause the mercury to move so far as to engage all three contacts E, fl, and '1, thus energizing both the light sources 8 and 9, and a still greater change of momentum will cause the mercury to shift so far as to engage only the central Contact d and the outermost contact l, thereby energizing the light source t alone. In this manner a visual indication of the approximate extent of momentum or inertia change is had.

The mea-ns for maintaining the momentum change indicating device in a constantly level position may be any suitable constant-level mechanism, such for example, as a gyroscope which has the characteristic of maintaining fixed posi-- tion in space when it is rotating at a high speed, otherwise referred to as rigidity in space.

The particular gyroscope device illustrated is the well-known gyro-horizoi. instrument, manufactured by the Sperry Gyrosct Je Company, Inc., which comprises an encased gyro ..Copc it universally suspended in suitable giznbals so that it may maintain a iixed position relative ."o the earth, regardless of the flight attitude of Lhe aircraft in which it is mounted. 'Elie gym-horizon in strument is positioned within the aircraft with the axis of the outermost gimhal i i dis; osed in a position parallel with the longitudinal couter lin@ menacer ci the aircraft and the encased gyroscope I8 is disposed with the axis of rotation of the gyroscope in a vertical position. Thus the aircraft may change its night attitude with respect to the vertical axisof the gyroscope without affecting its constant level position, as indicated by the dotted lines of Fig. 2, which show the relative position of the gyroscope lll and the outermost gimbal il when the aircraft is in a climb. The longitudinal axis A-A of the outer gimbal l I, however, will always remain parallel with the fore and aft axis of the aircraft and the gyroscope casing iii vwill turn therewith in any horizontal direction.

As shown, themomentum change indicator is iixedly mounted on the upper portion of the gyroscope casing id, the bracket 2 of the momentum change indicator being clamped between two nuts it and i3 threaded on a stud Hl which is integral with the` gyroscope casing it. 'Ihe bracket 2 is mounted on the gyroscope casing so that its longitudinal axis and the axis of the indicator tube l will lie in the same vertical plane as the axis A-A of the outer gimbal ii.

Thus, regardless of the flight attitude of the aircraft in which the device is mounted, the momentum change indicator will be held constantly in a vertical position with its axis at all times extending inthe fore and aft direction of the aircraft.

From the foregoing it will be seen that the devices necessary to maire the observation for determining'the wind velocity and wind direction are the change of momentum indicator, together with the constant level device, an air speed indicator and a compass. These devices may he combined in a panel, as shown in Fig. 3. Since a directional gyio such as manufactured by the Sperry Gyrosccpe Company, Inc., is a preferable instrument for indicating the direction of night, the particular panel illustrated comprises a directional-gym i6, a gym-horizon l'l on which the .momentum change indicating device is mounted,

an air speed indicator i3 and the means Si, 8.1, S and 9J for providing visual indication of inertia or momentum change.

The air speed indicator iS may be any suitable device for that purpose, such for example, as the air speed indicator manufactured by the Pioneer Instrument Company, Incorporated.

in operation of the momentum change indicator, any variation of the aircrafts inertia or momentum, which would occur during a variation of the ground speed of the aircraft, will cause the mercury contained in the momentum change indicator tube l to shift along the curved bottom surface of the tube in the direction opposite that at which the momentum or inertia change takes place, causing a circuit to be completed 'between the contacts located in the respective end of the tube i, so as to energize the respective visual indication means.

For example, should there be an increase in ground speed, or an acceleration of the aircraft, which is flying in the direction of the arrow l5 shown in Fig. 2, the mercury 3, due to its own inertia, will be caused to shift toward the contacts E, i and engaging iirst the contacts E and d to complete a circuit to the indicating means 8, or if the rate of acceleration is high enough the mercury will engage the contacts 6, d and 'i to energize' both the indicating means t and 9. or upon a still greater ground speed or momentum change in the direction of acceleration the mercury 3 will he caused to move so far as to engage Only the contacts i and 1, so that only the indithe undesired acceleration.

eating means il will be energized. In the case of deceleration, the mercury will shift to the opposite side of the tuoe i and engage the contacts CJ, di, and .i in the same manner as in 55 the case of acceleration, so that the indicating means 8i and 9.! will be energized.

Thus1 to keep'the plane at a substantially constent ground speed the pilot, by observing the indicating means il, 9, E i and Sii, will be instantly l@ advised of any change oi momentum and the din rection in which such change is taking piace, and need only climb or dive or decrease or increase the speed of his motors in order to compensate for or overcome the observed momentum change. For

E65 example, should the indicating means 8 end ii become energized to indicate acceleration, or increase oi ground speed, the pilot need only de crease the speed of his motors or climb to decrease the speed oi the aircraft, and thus compensate for The amount of compensation required is determined by Whether inn dicating means 8 alone is energized to indicate e. small or moderate momentum change, or whether il and 9 are energized, which indicates a somewhat greater momentum change, or whether the indicator il alone is energized, which indicates e. relatively large momentum change.

As shown, the indicating means 8 and il, or BJ and QJ are grouped on respective sides oi the air speed indicator, so .that the pilot may observe both the momentum change indications and the air speed, and in order to more readily determine vwhether the momentum change is in the direc tion of acceleration orv deceleration the respective 3J indicating means can be provided with different characteristics; for example, if lights are used as shown, those for acceleration may be colored green and those for deceleration colored red.

Thus, in the practice of my improved method of 49 determining Wind direction and velocity, the aircraft-need only be own through a 350 horizontal turn, as shown by the heavy lines and 'arrows' in Fig. e, meanwhile being maintained at a substantially constant ground speed or momentum.

45`As the aircraft is navigatori through the horizontel turn the air sneed indicator is observed, and the maximum minimum air speeds attained are noted, together with the direction in which the aircraft is iiying for the condition of mam- 50 mum or minimum air speed, after which the airship can be returned to its normal course. The wind velocity will then be determined by obtaining one-hali the ditl'eience between the maximum and minimum air speeds and the direction toward 55 which the Wind is blowing will be the direction in which the ship was :dying et the point of mini- 'moi/ingenti the point of maximum air speed will be attained when the aircraftis flying directly into the wind. Thus, with a constant ground speed the minimum air speed attained will be the actual ground speed less the wind velocity. and the maximum air speed will be the actual ground vSpedi plus the Wind. velocity. Therefore, with a constant ground speed during the period ofA observation, the actual wind velocity will be one-half the dierence between the maximum and minimum air speed indications, and the actual ground speed need not be known, so long as it is kept constant. Y

As an example, assuming that aircraft is navigated along the course of the heavy lines and arrows of the diagram shown in Fig. 4 and the wind direction is indicated by the broken lines and arrows, the point of minimum air speedwill be the point X and the point of maximum air speed will oe the point Y. Thus, if the air speed reading at the point X is 115 M. P. H. and the air speed reading at the pointY is 205 M. P. H., the actual Wind velocity will be one-half the difference between 205 and 115, or 45 M. P. H., the wind direction being noted by the compass reading `oi the direction in which the airship is flying at the point X. Y

Although but one specific yernlalxliment and practice 'of this invention is herein shown and described, it will be understood that details of velocity from an aircraft in flight, maneuvering said aircraft through a horizontal turn oi? substantially 360, maintaining said aircraft at a substantially constent ground speed during said turn by observing changes in said ground speed and compensating therefor by correctional ground speed variations, and determining the maximum and minimum air speeds of said aircraft and the respective directions of. :flight dur- 

